I recently made a substantial edit to this answer to the Q&A "Which spells benefit from the Spell Sniper feat?", that would make a good dupe target.
The help page on editing says:
Edits are expected to be substantial and to leave the post better than you found it.
I feel the edit I made is in line with those, along with covering a mistake in the original post (i.e. there are exceptions).
However previous Q&As on meta (Editing someone else's answer vs. commenting, and When editing, how drastic is too drastic?) have been inconclusive, and disagree on whether to add a comment or make an edit. The sole answer to the first Q&A says, in part:
When you think the answer is mostly good but you wish it would address an additional point
While mxyzplk's answer to the second Q&A says:
[...] edits shouldn't change the nature of the answer - if you're changing a yes to a no, that's bad [...] We edit to add info, to add clarification from comments so comments can be deleted, to copyedit... Whatever seems like it's improving the answer, while maintaining the point of the answer.
Did my edit to cover edge cases go too far, based on the above?